Systems and methods for non-orthogonal multiple access

ABSTRACT

A resource allocation method is provided for a non-orthogonal multiple access distribution of access network users communicatively coupled to a single transport medium. The method includes steps of allocating a first frequency and time domain resource to a first user and a second frequency and time domain resource to a second user of the access network users, obtaining channel information regarding a particular communication channel of the access network for which resources are allocated, grouping the first user with the second user based on an overlap of the first frequency and time domain resource with the second frequency and time domain resource, and assigning the first user to a different power allocation resource than the second user within the frequency and time domain overlap.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/201,452, filed Mar. 15, 2021. U.S. patent application Ser. No.17/201,452 is a continuation of U.S. patent application Ser. No.16/729,960, filed Dec. 30, 2019, now U.S. Pat. No. 10,951,314, issued onApr. 30, 2020. U.S. patent application Ser. No. 16/729,960 is acontinuation of U.S. patent application Ser. No. 16/180,912, filed Nov.5, 2018, now U.S. Pat. No. 10,523,324, issued on Dec. 31, 2019. U.S.patent application Ser. No. 16/180,912 claims the benefit of andpriority to U.S. Provisional Patent Application Ser. No. 62/581,339,filed Nov. 3, 2017. All of these prior applications are incorporatedherein by reference in their entireties.

BACKGROUND

The field of the disclosure relates generally to communication systemsand networks, and more particularly, to communications systems andnetworks employing non-orthogonal multiple access.

Conventional hybrid fiber-coaxial (HFC) architectures typically deployfiber strands from an optical hub to a fiber node, and often many shortcoaxial or fiber strands to cover the shorter distances from the fibernodes to a plurality of end users. Conventional Multiple ServiceOperators (MSOs) offer a variety of services, including analog/digitalTV, video on demand (VoD), telephony, and high speed data internet, overthese HFC networks, which utilize both optical fibers and coaxialcables, and which provide video, voice, and data services to the enduser subscribers. HFC networks are known to include a master headend,and the optical fiber strands carry the optical signals between theheadend, the hub, and the fiber node. Conventional HFC networks alsotypically include a plurality of coaxial cables to connect the fibernodes to the respective end users, and to carry radio frequency (RF)modulated analog electrical signals.

The HFC fiber node converts optical analog signals from the opticalfiber into the RF modulated electrical signals that are transported bythe coaxial cables to the end users/subscribers. In the conventional HFCnetwork, both the optical and electrical signals are analog, from thehub to the end user subscriber's home. Typically, a modem terminationsystem (MTS) is located at either the headend or the hub, and providescomplementary functionality to a modem of the respective end user.

The signal components of the conventional HFC fiber/coaxial cable linksexperience higher propagation attenuation at higher frequency. Theattenuation increases over distance and this attenuation effect isparticularly significant in coaxial cables. Thus, different users of thenetwork will experience difference system performance at differentdistances from the fiber node, at different operation frequencies.Conventional HFC networks, however, implement orthogonal multiple access(OMA) techniques to allocate resources orthogonally in the frequency andtime domains.

FIG. 1 is a graphical illustration depicting a conventional orthogonalmultiple access (OMA) two-dimensional frequency-time-power distribution100 of users 102. In the exemplary embodiment illustrated in FIG. 1 ,distribution 100 is depicted with respect to a conventional HFC networkthat implements a communication protocol such as the Data Over CableService Interface Specification (DOCSIS), or DOCSIS version 3.1 (D3.1).In this example, each of the several different users 102 are illustratedas occupying different frequency-time slots on (e.g., on a 2-D plane)and do not overlap with other users 102.

According to conventional OMA distribution 100, the OMA techniques ofdistribution 100 do not consider the respective variations experiencedby users 102 according to the distance of a particular user 102 from thenode, or the frequency slot at which that user 102 is operating. Moreparticularly, the conventional OMA techniques do not optimize resourceallocation based on these variations, thereby resulting in low spectralefficiency. Accordingly, it is desirable to provide techniques thatconsider the channel differences of different users and frequencies tooptimize network resource allocation, and in an equitable manner, toincrease the spectral efficiency and throughput of the network.

BRIEF SUMMARY

In an embodiment, a resource allocation method is provided for anon-orthogonal multiple access distribution of access network userscommunicatively coupled to a single transport medium. The methodincludes steps of allocating a first frequency and time domain resourceto a first user and a second frequency and time domain resource to asecond user of the access network users, obtaining channel informationregarding a particular communication channel of the access network forwhich resources are allocated, grouping the first user with the seconduser based on an overlap of the first frequency and time domain resourcewith the second frequency and time domain resource, and assigning thefirst user to a different power allocation resource than the second userwithin the frequency and time domain overlap.

In an embodiment, a resource allocation method is provided for anon-orthogonal multiple access distribution of access network userscommunicatively coupled to a single transport medium. The methodincludes steps of allocating a first frequency and time domain resourceto a first user and a second frequency and time domain resource to asecond user of the access network users, obtaining channel informationregarding a particular communication channel of the access network forwhich resources are allocated, grouping the first user with the seconduser based on an overlap of the first frequency and time domain resourcewith the second frequency and time domain resource, and assigning thefirst user to a different code allocation resource than the second userwithin the frequency and time domain overlap.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a graphical illustration depicting a conventional orthogonalmultiple access two-dimensional frequency-time-power distribution ofusers.

FIG. 2 is a graphical illustration depicting a non-orthogonal multipleaccess three-dimensional distribution of users, in accordance with anembodiment.

FIG. 3 is a flow diagram for an exemplary resource allocation processfor the non-orthogonal multiple access distribution depicted in FIG. 2 .

FIG. 4 is a partial schematic illustration of a communication systemconfigured to implement the allocation process depicted in FIG. 3 .

FIG. 5 is a graphical illustration depicting respective attenuationversus frequency plots for the first and second users depicted in FIG. 4.

FIG. 6 is a graphical illustration depicting an exemplary derivationtechnique for maximizing spectral efficiency of the first and secondusers depicted in FIG. 4 .

FIG. 7 is a graphical illustration depicting a constellation plot ofsuperimposed signals corresponding to the first and second usersdepicted in FIG. 4 .

FIG. 8 is a graphical illustration demonstrating a capacity tradeoffeffect between the first and second users depicted in FIG. 4 accordingto the conventional orthogonal multiple access technique compared withthe present non-orthogonal multiple access techniques.

FIG. 9 is a graphical illustration demonstrating a capacity tradeoffeffect between the first and second users depicted in FIG. 4 accordingto the conventional orthogonal multiple access technique compared withthe present non-orthogonal multiple access techniques.

FIG. 10 is a graphical illustration depicting a distance versus capacityimprovement effect for the second user depicted in FIG. 4 .

FIG. 11 is a graphical illustration depicting a noise level versuscapacity improvement effect for the second user depicted in FIG. 4according to the conventional orthogonal multiple access techniquecompared with the present non-orthogonal multiple access techniques.

Unless otherwise indicated, the drawings provided herein are meant toillustrate features of embodiments of this disclosure. These featuresare believed to be applicable in a wide variety of systems including oneor more embodiments of this disclosure. As such, the drawings are notmeant to include all conventional features known by those of ordinaryskill in the art to be required for the practice of the embodimentsdisclosed herein.

DETAILED DESCRIPTION

In the following specification and the claims, reference will be made toa number of terms, which shall be defined to have the followingmeanings.

The singular forms “a,” “an,” and “the” include plural references unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

As used herein, the term “database” may refer to either a body of data,a relational database management system (RDBMS), or to both, and mayinclude a collection of data including hierarchical databases,relational databases, flat file databases, object-relational databases,object oriented databases, and/or another structured collection ofrecords or data that is stored in a computer system.

Furthermore, as used herein, the term “real-time” refers to at least oneof the time of occurrence of the associated events, the time ofmeasurement and collection of predetermined data, the time for acomputing device (e.g., a processor) to process the data, and the timeof a system response to the events and the environment. In theembodiments described herein, these activities and events occursubstantially instantaneously.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” “approximately,” and “substantially,” are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged; such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.

The present embodiments advantageously improve over the conventional OMAtechniques, described above, by implementing non-orthogonal multipleaccess (NOMA) to expand the channel resource space into a thirddimension, namely, that of the power domain (i.e., PD-NOMA) and/or thecode domain (i.e., CD-NOMA). The present systems and methods aretherefore able to take the channel difference between different usersand different frequencies into consideration, and then optimize theresource allocation of the network (e.g., an HFC network) in a moreequitable manner. According to the techniques described herein, both thespectral efficiency and the throughput of the network are significantlyincreased, while also advantageously generating more use cases, andincluding more classes of users, than may be realized according to theconventional techniques.

FIG. 2 is a graphical illustration depicting a non-orthogonal multipleaccess (NOMA) three-dimensional distribution 200 of resource blocks 202for individual users. Distribution 200 represents an exemplarythree-dimensional space of the resources allocated to various users thatmay occupy the same frequency-time slot in two dimensions, but which mayoverlap in a third dimension of power (e.g., PD-NOMA) and/or code (e.g.,CD-NOMA). In this example, each resource block 202 indicates athree-dimensional representation of resources allocated to a particularuser. In some cases, multiple different resource blocks 202 may beallocated to the same user. Techniques for allocating resources tousers, and to groups of users, may be performed as described below, forvarious purposes and according to particular constraints, in order tomaximize overall capacity, while also ensuring throughput to individualusers and user groups. The following examples are described with respectto an HFC network communication system for ease of explanation, but notin a limiting sense. The person of ordinary skill in the art willunderstand how the principles of the present embodiments are applicableto other types of communication networks and protocols.

FIG. 3 is a flow diagram for an exemplary resource allocation process300 for NOMA distribution 200, FIG. 2 . In the exemplary embodiment,process 300 may allocate channel resources with respect to an HFC systemimplementing NOMA. Process 300 is described herein with reference to anexemplary communication system 400 illustrated in FIG. 4 , below. Exceptwhere described to the contrary, the particular order of steps inprocess 300 are provided for purposes of illustration, and not in alimiting sense.

In exemplary operation, process 300 begins at step 302, in which afrequency-time resource is allocated to a set of users 402 (FIG. 4 ,below). In an exemplary embodiment of step 302, the two-dimensionalfrequency-time portion (i.e., the rectangular area on the frequency-timeplane) of each three-dimensional resource block is assigned to users 402(six, in this example) that are communicatively connected to a same HFCplant (e.g., transport medium 408, FIG. 4 , below) belonging to the sameservice group. In step 304, process 300 obtains channel informationregarding the particular channel of communication system 400 for whichresources are allocated. In an exemplary embodiment of step 304, thechannel information includes the frequency response andsignal-to-noise-ratio (SNR)/noise level at each user 402.

In step 306, based on the channel information, the set of users 402 aredivided into groups. In an exemplary embodiment of step 306, each usergroup is formed of users that occupy the same two-dimensionalfrequency-time resource, but at a different power/code domain level.Accordingly, in some embodiments, each user 402 may belong to multiplegroups at the same time (e.g., users 402(4), 402(5), 402(6)). In thiscase, different users 402 are capable of occupying different amounts offrequency-time resources, that is, different users may have differentsizes and shapes of resource blocks 202. In an embodiment, user groupingmay be performed according to criteria such as maximized capacity,system requirements satisfaction, service level agreement fulfillment,and present or dynamic traffic demands. In step 308, within each group,process 300 calculates the optimal power/code allocation among users402.

FIG. 4 is a partial schematic illustration of a communication system 400configured to implement allocation process 300, FIG. 3 . In theexemplary embodiment, communication system 400 is an HFC systemimplementing the present NOMA techniques for users 402, and includes anode 404 (e.g., a fiber node), and a plurality of taps 406 forconnecting respective users 402 to a signal transport medium 408 (e.g.,a fiber strand, coaxial cable, etc.). In exemplary operation of system400, first user 402(1) and second user 402(2) are depicted to occupy thesame two-dimensional frequency-time slot, and thus may belong to thesame group (e.g., step 306, FIG. 3 ). When seen three-dimensionallythough, first user 402(1) and second user 402(2) are separated in thepower/code domain according to the power/code allocation determined bythe system (e.g., step 308, FIG. 3 ). In an exemplary embodiment, system400 is configured to perform the power/code allocation according to,criteria including, without limitation, maximized capacity, systemrequirements satisfaction, service level agreement fulfillment, andpresent or dynamic traffic demands, as described above.

FIG. 5 is a graphical illustration depicting respective attenuationversus frequency plots 500, 502 for first and second users 402(1),402(2), FIG. 4 . For ease of explanation, an exemplary description ofgain and signaling effects in FIG. 5 are limited to only two users 402(i.e., plots 500, 502), but the person of ordinary skill in the art willunderstand how these principles apply with respect to more than twousers on a cable plant. In an exemplary embodiment depicted in FIG. 5 ,first and second users 402(1), 402(2) occupy the same frequency-timeslot, but are separated in the power domain.

For further ease of explanation, in this example, it is assumed that (1)capacity is the exemplary criterion used to determine the resourceallocation in the power domain over a frequency-time slot, (2) thefrequency-time slot is fixed by other preconditions or constraints ofthe overall allocation, (3) the frequency range of the givenfrequency-time slot is relatively small, (4) the total power for 402(1),402(2) over the given frequency-time slot is fixed by otherpreconditions or constraints of the overall allocation (and is denotedas P), and (5) the channel is time-invariant. The person of ordinaryskill in the art though, will understand that these assumptions areprovided by way of example, and not in a limiting sense.

In the exemplary embodiment depicted in FIG. 5 , first user 402(1) andsecond user 402(2) are located at different physical locations withinthe HFC network of communication system 400. In this example, first user402(1) is located nearer in proximity to node 404 with respect to seconduser 402(2), which is located farther away from node 404. Therefore,irrespective of any pre-emphasis, second user 402(2) will experiencesignificantly more power variation, that is, attenuation, over afrequency range, as illustrated by the greater slope to plot 502 (user2)in comparison with the more linear, horizontal slope of plot 500(user1). This variation difference results in the difference ofattenuation (e.g., A₁ versus A₂) exhibited by first user 402(1) andsecond user 402(2), respectively, at a given frequency f_(g).

In the example illustrated in FIG. 5 , a two-dimensional cross-sectionof the resource blocks 202(1), 202(2) are depicted with respect to atwo-dimensional cross-section of the entire distribution 200. As may beseen from this exemplary illustration, second user 402(2) has a lowerattenuation value A₂ at frequency f_(g), and the average attenuationvalues within the frequency slot that includes frequency f_(g) may beapproximated to A₁ and A₂ (in dB) for first user 402(1) and second user402(2), respectively.

Assuming, for purposes of this description, that the additive whiteGaussian noise (AWGN) channels and Gaussian noise have a power of Nwithin the frequency slot f_(g) at a receiver side of system 400, thespectral efficiency η of first user 402(1) and second user 402(2) withinthe frequency slotf_(g) may be respectively represented by:

$\begin{matrix}{\eta_{1} \leq {\log_{2}\left( {1 + \frac{a_{1}{Px}}{N + {{a_{1}\left( {1 - x} \right)}P}}} \right)}} & \left( {{Eq}.1} \right)\end{matrix}$ forfirstuser402(1)/user1, andby: $\begin{matrix}{\eta_{2} \leq {\log_{2}\left( {1 + \frac{{a_{2}\left( {1 - x} \right)}P}{N}} \right)}} & \left( {{Eq}.2} \right)\end{matrix}$for second user 402(2)/user2, where α₁₌10^(∧(−A) ₁/10), α₂=10^(158 (−A)₂/10), P is the total power budget for both users at the transmitterside, and 0≤x≤1 is the proportion of power for first user 402(1). Thetotal spectral efficiency η_(total) may then be represented as:

$\begin{matrix}{\eta_{total} = {{\eta_{1} + \eta_{2}} \leq {\log_{2}\left( \frac{N^{2} + {\left( {a_{1} + a_{2}} \right){PN}} + {a_{1}a_{2}P^{2}} - {a_{2}{P\left( {N + {a_{1}P}} \right)}x}}{N^{2} + {a_{1}{PN}} - {a_{1}{PNx}}} \right)}}} & \left( {{Eq}.3} \right)\end{matrix}$

Accordingly, in the embodiments described above, including allocationprocess 300, system 400 is advantageously configured to enablemaximization of η₁, η₂, and/or η_(total) according to a desired purposeof the system operator, and/or preconditions or constraints that may beplaced on the system and its operation. In some embodiments, resourceallocation may be further realized by adjusting value of x.

FIG. 6 is a graphical illustration depicting an exemplary derivationtechnique 600 for maximizing spectral efficiency of first and secondusers 402(1), 402(2), FIG. 4 . The exemplary embodiment illustrated inFIG. 6 is depicted with respect to a derivation of maximum η₁ and η₂implementing PD-NOMA. The person of ordinary skill in the art though,will appreciate that the principles described herein are applicable toother NOMA techniques, such as CD-NOMA, etc.

In an exemplary embodiment, the spectral efficiencies η₁ and η₂ aremaximized for first user 402(1) and second user 402(2), respectively.Thus, by traversing the value x over [0, 1], an upper boundary curve 602of (η₁, η₂) may be derived for the PD-NOMA implementation. With respectto the exemplary embodiment depicted in FIG. 6 , the area under upperboundary curve 602 is considered to be achievable. FIG. 6 furtherillustrates, for comparison, a counterpart curve 604 representing anupper limit achievable through the conventional OMA technique. As can beseen from the comparison, the greater boundary is achievableimplementing the present NOMA techniques.

In an exemplary embodiment of technique 600, a constraint 606 of η₁=η₂is applied, which intersects both curves 602, 604 at points C and D,respectively. Thus, when compared with OMA value (i.e., point D) ofcounterpart curve 604, the spectral efficiency of both η₁ and η₂ areimproved for the PD-NOMA implementation (i.e., point C).

FIG. 7 is a graphical illustration depicting a constellation plot 700 ofsuperimposed signals 702 corresponding to first and second users 402(1),402(2), FIG. 4 . In the exemplary embodiment illustrated in FIG. 7 ,constellation plot 700 is depicted with respect to two superimposed QPSKsignals implementing PD-NOMA, and using derivation technique 600. Inthis example, the modulation format is designated to approach themaximum spectral efficiency η at point C on upper boundary curve 602.Using the respective amplitudes of constellation 700, the value for x atpoint C may be derived.

FIG. 8 is a graphical illustration demonstrating a capacity tradeoffeffect 800 between first and second users 402(1), 402(2), FIG. 4 ,according to the conventional OMA technique compared with the presentNOMA techniques. In the exemplary embodiment illustrated in FIG. 8 ,trade-off effect 800 demonstrates the simulation results of a capacitytrade-off between user1 and user2 at a distance of 300 ft from the node(e.g., node 404, FIG. 4 ), for an OMA case 802 and a NOMA case 804.

In this example, the respective resource blocks 202 of first and secondusers 402(1), 402(2) (i.e., user1 and user2) are assumed to occupy atotal bandwidth of 20 MHz, and at a central frequency of 1 GHz afterfrequency-time allocation and user grouping. Referring back to FIG. 4 ,the tap to which user1 connects (e.g., tap 406(1)) is, in this example,100 ft away from fiber node 404, while the tap to which user2 connects(e.g., tap 406(2)) is 300 ft away from node 404. In this simulation,taps 406 were communicatively connected to node 404 by 75-Ohm 0.5-inchhardline cables, and the noise density at the receiver end of simulatedsystem 400 was 25-dB lower than the transmitted signal power density.

Accordingly, when compared with first user 402(2), second user 402(2)experiences higher attenuation at 1 GHz due to the fact that second user402(1) is farther away from node 404. Thus, because first and secondusers 402(1), 402(2) share the same frequency resource (20 MHz, in thisexample), the relative capacity both users has a tradeoff relationship.As can be seen from the exemplary effect 800 depicted in FIG. 8 , thetradeoff for both of first and second users 402(1), 402(2) isdemonstrated along both an OMA curve 806 and a PD-NOMA curve 808.Additionally, when and equal capacity constraint 810 is applied as acriterion for effect 800, it can be seen that, at point 812 on NOMAcurve 808, 7 Mbps (i.e. 10.6%) of higher capacity is realized incomparison with a corresponding equal-capacity point 814 on OMA curve806.

Accordingly, implementing OMA techniques, trade-off effect 800demonstrates, in this simulation example, that 1001.2-1010 MHz isallocated to first user 402(1) and 990-1001.2 MHz is allocated to seconduser 402(2). However, in contrast, the implementation of PD-NOMA enables6.41% of the total transmitted power to be allocated to first user402(1) and 93.59% of the transmitted power to be allocated to seconduser 402(2).

FIG. 9 is a graphical illustration demonstrating a capacity tradeoffeffect 900 between first and second users 402(1), 402(2), FIG. 4 ,according to the conventional OMA technique compared with the presentNOMA techniques. Tradeoff effect 900 is similar to tradeoff effect 800,FIG. 8 , except that tradeoff effect 900 demonstrates simulation resultsfor second user 402(2) located 500 ft from node 404, for an OMA case 902and a NOMA case 904, as opposed to the 300 ft distance described abovewith respect to FIG. 8 . Accordingly, a higher improvement may beobserved from the implementation of the present NOMA techniques forusers 402 located at even greater distances from node 404.

Also similar to effect 800, effect 900 depicts an OMA curve 906 and aNOMA curve 908, and applies an equal capacity constraint 910 as acriterion. In this example, it may be seen that, at point 912 on NOMAcurve 908, 11.9 Mbps (i.e. 21.8%) of higher capacity is realized incomparison with a corresponding equal-capacity point 914 on OMA curve906. Additionally, implementing OMA techniques, 1001.2-1010 MHz is againallocated to first user 402(1) and 990-1001.2 MHz is again allocated tosecond user 402(2). However, in this example, the implementation ofPD-NOMA enables 5% of the total transmitted power to be allocated tofirst user 402(1) and 95% of the transmitted power to be allocated tosecond user 402(2).

FIG. 10 is a graphical illustration depicting a distance versus capacityimprovement effect 1000 for second user 402(2), FIG. 4 . In theexemplary embodiment, improvement effect 1000 demonstrates, throughsimulation, the results achieved by implementation of the present NOMAtechniques (e.g., in comparison with conventional OMA techniques). Moreparticularly, improvement effect 1000 depicts a relationship curve 1002between the location of second user 402(2) and the capacity improvementusing NOMA, when first user 402(1) is fixed at a location 100 ft awayfrom the node 404 in these simulations. Relationship curve 1002therefore becomes a valuable tool for grouping users (e.g., step 306 ofprocess 300, FIG. 3 ), based on the respective locations of varioususers, as well as other chosen criteria of the system.

FIGS. 11 is a graphical illustration depicting a noise level versuscapacity improvement effect 1100 for second user 402(2), FIG. 4 ,according to the present NOMA techniques compared with the conventionalOMA technique. In an exemplary embodiment, the capacity improvement mayalso be determined based on respective noise level experienced by aparticular user at various distances from the node. Improvement effect1100 depicts the capacity improvement (i.e., the vertical axis, in %)under different noise levels (i.e., the horizontal axis, in dB) for afirst condition 1102 when second user 402(2) is located 300 ft from node404, and for a second condition 1104 when second user 402(2) is located500 ft away from node 404. Under first condition 1102 (i.e., 300 ft) afirst maximal point 1106 is found when the noise level is approximately−17 dB, while under second condition 1104 (i.e., 500 ft), a secondmaximal point 1108 is found when the noise level is approximately −23dB. The respective curves of first and second conditions 1102, 1104therefore also provide valuable tool for grouping users (e.g., step 306of process 300, FIG. 3 ), based on the respective noise levels andlocations of various users, as well as other chosen criteria of thesystem.

The present embodiments are described above with respect to HFC networksby way of example, and not in a limiting sense. The person of ordinaryskill in the art will appreciate how the systems and methods describedherein are also applicable to the optical fiber segments in the HFCnetwork, as well as a passive optical network (PON) architecture thatutilizes optical fiber segments in multiple fiber nodes at endpoints,which may be analogous to the various users described with respect tothe present embodiments. The NOMA techniques described herein are alsoprovided for illustrative purposes, but are not intended to be limiting.Other NOMA techniques, for example, may also be implemented within thescope of the present embodiments, including without limitationMulti-User Superposition Transmission (MUST), Sparse Code MultipleAccess (SCMA), Pattern Division Multiple Access (PDMA), LatticePartition Multiple Access (LPMA), and/or Multi-User Shared Access(MUSA).

The person of ordinary skill will further appreciate that the presenttechniques are generally applicable to access systems having a powerdomain and/or a code domain, and which adopt non-orthogonal signal spacein an HFC network. As featured above, the principles of the presentsystems and methods are described with respect to two users separated inthe power/code domain. Nevertheless, the person of ordinary skill in theart will appreciate that these principles apply in the case of more thantwo users separated in the power/code domains. It will further beappreciated, from the description herein and the accompanying drawings,that the present techniques for optimizing the power/code domains arenot exclusive of optimization techniques for the frequency and timedomains. That is, the present embodiments may be employed as jointallocation and/or joint optimization techniques for the power/codedomain in a complementary and/or simultaneous fashion withallocation/optimization techniques of the frequency and time domains.

Exemplary embodiments of systems and methods for optimizingnon-orthogonal multiple access are described above in detail. Thesystems and methods of this disclosure though, are not limited to onlythe specific embodiments described herein, but rather, the componentsand/or steps of their implementation may be utilized independently andseparately from other components and/or steps described herein.

Although specific features of various embodiments of the disclosure maybe shown in some drawings and not in others, this is for convenienceonly. In accordance with the principles of the disclosure, a particularfeature shown in a drawing may be referenced and/or claimed incombination with features of the other drawings.

Some embodiments involve the use of one or more electronic or computingdevices. Such devices typically include a processor or controller, suchas a general purpose central processing unit (CPU), a graphicsprocessing unit (GPU), a microcontroller, a reduced instruction setcomputer (RISC) processor, an application specific integrated circuit(ASIC), a programmable logic circuit (PLC), a field programmable gatearray (FPGA), a DSP device, and/or any other circuit or processorcapable of executing the functions described herein. The processesdescribed herein may be encoded as executable instructions embodied in acomputer readable medium, including, without limitation, a storagedevice and/or a memory device. Such instructions, when executed by aprocessor, cause the processor to perform at least a portion of themethods described herein. The above examples are exemplary only, andthus are not intended to limit in any way the definition and/or meaningof the term “processor.”

This written description uses examples to disclose the embodiments,including the best mode, and also to enable any person skilled in theart to practice the embodiments, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the disclosure is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal language of the claims.

The invention claimed is:
 1. A resource allocation method for anon-orthogonal multiple access (NOMA) distribution of access networkusers communicatively coupled to a transport medium of a hybrid fibercoaxial (HFC) access network, the method comprising the steps of:allocating resources of the access network to a plurality of resourceblocks, each resource block of the plurality of resource blocks having(i) a first dimension indicating time resources, (ii) a second dimensionindicating frequency resources, and (iii) a third dimension differentfrom the first and second dimensions; obtaining channel informationregarding a particular communication channel of the access network forwhich the resources are allocated; and assigning a first resource blockto a first user of the NOMA distribution of access network users, and asecond resource block to a second user of the NOMA distribution ofaccess network users, wherein the first resource block overlaps with thesecond resource block in at least one of the first, second, and thirddimensions, and wherein the first resource block does not overlap withthe second resource block in another one of the first, second, and thirddimensions.
 2. A resource allocation method for a non-orthogonalmultiple access (NOMA) distribution of access network userscommunicatively coupled to a transport medium of an access network, themethod comprising the steps of: allocating resources of the accessnetwork to a plurality of resource blocks, each resource block of theplurality of resource blocks having (i) a first dimension indicatingtime resources, (ii) a second dimension indicating frequency resources,and (iii) a third dimension different from the first and seconddimensions; obtaining channel information regarding a particularcommunication channel of the access network for which the resources areallocated; and assigning a first resource block to a first user of theNOMA distribution of access network users, and a second resource blockto a second user of the NOMA distribution of access network users,wherein the first resource block overlaps with the second resource blockin at least one of the first, second, and third dimensions, wherein thefirst resource block does not overlap with the second resource block inanother one of the first, second, and third dimensions, and wherein thechannel information includes a frequency response and asignal-to-noise-ratio (SNR) of the first user and the second user.
 3. Aresource allocation method for a non-orthogonal multiple access (NOMA)distribution of access network users communicatively coupled to atransport medium of an access network, the method comprising the stepsof: allocating resources of the access network to a plurality ofresource blocks, each resource block of the plurality of resource blockshaving (i) a first dimension indicating time resources, (ii) a seconddimension indicating frequency resources, and (iii) a third dimensiondifferent from the first and second dimensions; obtaining channelinformation regarding a particular communication channel of the accessnetwork for which the resources are allocated; and assigning a firstresource block to a first user of the NOMA distribution of accessnetwork users, and a second resource block to a second user of the NOMAdistribution of access network users, wherein the first resource blockoverlaps with the second resource block in at least one of the first,second, and third dimensions; and grouping the first user with thesecond user based on the overlap of the first resource block with thesecond resource block.
 4. The method of claim 3, wherein the step ofgrouping is further based on a respective difference in noise levelbetween the first user and the second user.
 5. The method of claim 3,wherein the step of grouping is further based on a distance of the firstuser from a node of the access network relative to a distance of thesecond user from the node.
 6. The method of claim 1, wherein the thirddimension indicates one of (i) power resources, and (ii) code resources.7. The method of claim 6, wherein each resource block has a fourthdimension indicating the other of the respective power resources andcode resources.
 8. The method of claim 7, wherein the first and secondresource blocks overlap in the first, second, and fourth dimensions, butdo not overlap in the third dimension.
 9. A resource allocation methodfor a non-orthogonal multiple access (NOMA) distribution of accessnetwork users communicatively coupled to a transport medium, the methodcomprising the steps of: allocating (i) a first resource block to afirst user of the NOMA distribution of access network users, and (ii) asecond resource block to a second user of the NOMA distribution ofaccess network users, wherein the first and second resource blocks aredefined by a virtual coordinate system having at least three dimensions,including (i) a frequency dimension, (ii) a time dimension, and (iii) athird dimension different from the frequency and time dimensions;wherein the first and second resource blocks (i) overlap in at least onedimension of the virtual coordinate system, and (ii) do not overlap inanother dimension of the virtual coordinate system, and wherein thevirtual coordinate system includes a fourth dimension different from thefirst, second, and third dimensions.
 10. The method of claim 9, whereinthe first and second resource blocks do not occupy the same virtualspace within the virtual coordinate system.
 11. The method of claim 9,wherein the third dimension is a power dimension, and the fourthdimension is a coding scheme dimension.
 12. The method of claim 9,wherein the third dimension is a coding scheme dimension, and the fourthdimension is a power dimension.
 13. The method of claim 9, wherein theaccess network is configured to implement non-orthogonal multiple access(NOMA) distribution of the first and second resource blocks.
 14. Themethod of claim 9, wherein the first and second resource blocks overlapin frequency and do not overlap in time.
 15. The method of claim 9,wherein the first and second resource blocks overlap in time and do notoverlap in frequency.
 16. The method of claim 9, wherein the firstresource block is allocated a first power level in the third dimensiondifferent from a second power level allocated to the second resourceblock.
 17. The method of claim 9, wherein a first power level allocatedto the first resource block in the third dimension is substantiallyequal to a second power level allocated to the second resource block.18. The method of claim 9, wherein the first resource block is allocateda first coding scheme in the third dimension different from a secondcoding scheme allocated to the second resource block.